The present invention relates to a vapor tube structure in a gas turbine disposed between a casing and a member-to-be-supported such as a blade ring supported by the casing. More particularly, this invention relates to a vapor tube structure in a gas turbine capable of absorbing and following thermal expansion/contraction difference between a casing and a member-to-be-supported.
In gas turbines of recent years, a structure f or cooling stationary blades is employed for enhancing efficiency. As a refrigerant for cooling the stationary blades, vapor is used. As a gas turbine of this kind, there is one described in Japanese Patent Application Laid-open No. 11-182205 filed by the present applicant. The gas turbine described in this publication will be explained below with reference to FIG. 12 and FIG. 13.
In FIG. 12, a reference number 100 represents a blade ring. The blade ring 100 is supported by a casing (not shown). The blade ring 100 comprises semi-annular shaped members which are combined with each other into an annular shape such that they can be detached in the vertical direction. In the blade ring 100, a plurality of (e.g., 32) front stage stationary blades (e.g., first stage stationary blades) 101 and rear stage stationary blades (e.g., second stage stationary blades) 102 which are arranged in a form of a ring. In some of the vapor tube structures in the gas turbine, third stage stationary blades, fourth stage stationary blades, fifth stage stationary blades, and so on are arranged in a form of a ring.
The blade ring 100 is of an integral structure integrally comprising a portion where the front stage stationary blades 101 are arranged and a portion where the rear stage stationary blades 102 are arranged. In addition to the blade ring integral structure, as a vapor tube structure in the gas turbine, there exists a blade ring separate type structure in which a blade ring having front stage stationary blades and a blade ring having rear stage stationary blades are separately formed and the blade ring on the side of the first stage stationary blade and the blade ring on the side of the rear stage stationary blade are connected to each other through a separate member.
The blade ring 100 is provided therein with a vapor supply passage 103, a vapor communication passage 104 and a vapor recovery passage 105. Vapor tubes (not shown) are respectively connected to the vapor supply passage 103 and the vapor recovery passage 105. On the other hand, the vapor tube is fixed to the casing. As a result, the vapor tube is disposed between the casing and the blade ring 100 as the member-to-be-supported. The vapor supply passage 103, the vapor communication passage 104 and the vapor recovery passage 105 are provided at least one each for the semi-annular shaped blade ring 100. On the other hand, in the plurality of front stage stationary blades 101 and the rear stage stationary blades 102, cooling vapor passages 106 and 107 are provided, respectively.
A first branch tube 108, a second branch tube 109, a third branch tube 110, a fourth branch tube 111 are respectively disposed between the vapor supply passage 103 and the cooling vapor passage 106 of the plurality of front stage stationary blades 101, between the vapor communication passage 104 and the cooling vapor passage 106 of the plurality of front stage stationary blades 101, between the vapor communication passage 104 and the cooling vapor passage 107 of the plurality of rear stage stationary blades 102, and between the vapor recovery passage 105 and the cooling vapor passage 107 of the plurality of the rear stage stationary blade 102.
A rotor (not shown) is rotatably mounted to the casing, and rotor blades (e.g., first stage rotor blades) 112 are annularly arranged.
The rotor blade 112 is arranged downstream from the stationary blades 101 and 102. The rotor blade 112 is arranged between the front stage stationary blade 101 and the rear stage stationary blade 102. A chip of the rotation side rotor blade 112 is opposed to the fixed side blade ring 100 through a clearance 113. It is important maintain the clearance 113 uniformly so as to enhance the efficiency of the gas turbine.
If the gas turbine is actuated, high temperature and high pressure combustion gas (not shown) passes through the front stage stationary blade 101, the rotor blade 112 and the rear stage stationary blade 102 to rotate the rotor blade 112 and the rotor side, thereby obtaining motive power.
Cooling vapor shown with solid arrows in FIG. 12 is supplied to the vapor supply passage 103 through the vapor tube. Then, the cooling vapor is distributed to cooling vapor passages 106 of the plurality of front stage stationary blades 101 from the vapor supply passage 103 through the first branch tube 108. The distributed cooling vapors passes through the cooling vapor passages 106 to cool the plurality of front stage stationary blades 101.
The cooling vapors which cooled the front stage stationary blades 101 pass through the second branch tube 109 and are collected into the vapor communication passage 104, and from the vapor communication passage 104, the vapors pass the third branch tube 110 and are again distributed into the cooling vapor passages 107 of the plurality of rear stage stationary blades 102. The distributed cooling vapors pass through the cooling vapor passages 107 to cool the plurality of rear stage stationary blades 102.
The cooling vapors which cooled the rear stage stationary blades 102 pass the fourth branch tube 111 and are again collected into the vapor recovery passage 105, and from the vapor recovery passage 105, the vapors are recovered through the vapor tube. The recovered vapors are reused.
In the above-described prior art gas turbine, the combustion gas tends to be heated to high temperature for enhancing the efficiency. Thus, there is thermal expansion/contraction difference between the casing and the member-to-be-supported.
In the vapor tube in the above-described prior art gas turbine, however, there is no means which absorbs and follows the thermal expansion/contraction difference between the casing and the member-to-be-supported. Therefore, there is an adverse possibility that vapor may leak from the conventional vapor tube.
It is an object of the present invention to provide a vapor tube structure in the gas turbine capable of absorbing and following the thermal expansion/contraction difference between the casing and the member-to-be-supported.
The vapor tube structure according to the present invention is disposed between a casing and a member-to-be-supported supported by the casing. This vapor tube structure comprises at least one first connecting tube fixed to the casing, at least one second connecting tube fixed to the member-to-be-supported, and a flexible structure provided between the first connecting tube and the second connecting tube.
As a result, it is possible to absorb and follow the thermal expansion/contraction difference between the member-to-be-supported and the casing by the flexible structure. Thus, it is possible to prevent vapor from leaking from the vapor tube disposed between the member-to-be-supported and the casing.
Other objects and features of this invention will become apparent from the following description with reference to the accompanying drawings.